Thank you Josh, my next move will be to get a different memory. Like you say, Even an MSV11DDD will help sort it out. I only need enough to get into ODT, and maybe run some XXDP. I have tried two CPUs and two J boards, so it is either the memory of backplane!
cheers, Nigel On 2021-10-21 4:29 a.m., Joshua Rice via cctech wrote: > > > > ------ Original Message ------ > From: "Nigel Johnson Ham via cctech" <[email protected]> > To: "Jerry Weiss via cctech" <[email protected]> > Sent: Thursday, 21 Oct, 2021 At 01:10 > Subject: Re: Looking for info on memory > Thanks for that, but unfortunately it is crashing into ODT and not > accepting input from the console, which I remember was a symptom of no > bank 0 memory. > Now,of course, it could be the receiver chip in the J board (I used to > make a lot of money changing them ) but I have tried two separate J > boards. > Of course if it is 4 MB, it must be in bank zero. > cheers, > Nigel > > > > I've not had any experience with third-party Q-BUS modules, with > nearly all my PDP-11's being built out of DEC cards, purely for the > reason that documentation is easy to find. However, one thing i do > remember reading up on is this: "NOTE WELL: For reasons which seem > utterly incomprehensible, many boards designed for Q/CD slots (such as > PMI <https://gunkies.org/wiki/Private_Memory_Interconnect> cards) do > not avoid the QBUS pins on the CD connectors which contain 'hazardous' > (to TTL circuitry) voltages. Plugging such a card into a Q/Q backplane > will generally destroy the card." > https://gunkies.org/wiki/QBUS#Backplanes > <https://gunkies.org/wiki/QBUS#Backplanes> . > > > Some of the later quad-height DEC memory modules had either jumpers or > resistors/fuses/not-sure-what-they-are that could be snipped out to > convert between Q/Q and Q/CD slots. I've seen this on MSV11-P cards. > It's entirely possible that the card wasn't configured correctly, and > at some point got fried by the mismatch between Q/CD and Q/Q. > > I would definitely recommend obtaining another memory board and swap > it in. Smaller capacity QBUS memory boards are usually quite cheap and > plentiful, so getting a 64K/128k card isn't impossible and won't break > the bank. It would at least help diagnose if it's the memory board, or > if the issues are deeper seated in your backplane or CPU module. > > I would also add, make sure your backplane is clean and not damaged. > It's an easy thing to overlook, but corrosion, damaged traces, damaged > pins, and general detritus can lead to all sorts of funky malfunctions. > > Cheers > > Josh Rice >
